From patchwork Fri May 10 19:56:17 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 10939475 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3093E1390 for ; Fri, 10 May 2019 20:02:31 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1FC0428C9B for ; Fri, 10 May 2019 20:02:31 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1439F28CCD; Fri, 10 May 2019 20:02:31 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4702428C9B for ; Fri, 10 May 2019 20:02:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728246AbfEJUCS (ORCPT ); Fri, 10 May 2019 16:02:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:55188 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727885AbfEJUBK (ORCPT ); Fri, 10 May 2019 16:01:10 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 802A9218CD; Fri, 10 May 2019 20:01:08 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.92) (envelope-from ) id 1hPBhb-0006iv-L1; Fri, 10 May 2019 16:01:07 -0400 Message-Id: <20190510200107.536391771@goodmis.org> User-Agent: quilt/0.65 Date: Fri, 10 May 2019 15:56:17 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Cc: Arnaldo Carvalho de Melo , Ingo Molnar , Jiri Olsa , Namhyung Kim , Andrew Morton , Tzvetomir Stoyanov Subject: [PATCH 11/27] tools/lib/traceevent: Man pages for event handler APIs References: <20190510195606.537643615@goodmis.org> MIME-Version: 1.0 Sender: linux-trace-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Tzvetomir Stoyanov Create man pages for libtraceevent APIs: tep_register_event_handler() tep_unregister_event_handler() Link: http://lore.kernel.org/linux-trace-devel/20190503091119.23399-11-tstoyanov@vmware.com Signed-off-by: Tzvetomir Stoyanov Signed-off-by: Steven Rostedt (VMware) --- .../libtraceevent-reg_event_handler.txt | 156 ++++++++++++++++++ 1 file changed, 156 insertions(+) create mode 100644 tools/lib/traceevent/Documentation/libtraceevent-reg_event_handler.txt diff --git a/tools/lib/traceevent/Documentation/libtraceevent-reg_event_handler.txt b/tools/lib/traceevent/Documentation/libtraceevent-reg_event_handler.txt new file mode 100644 index 000000000000..53d37d72a1c1 --- /dev/null +++ b/tools/lib/traceevent/Documentation/libtraceevent-reg_event_handler.txt @@ -0,0 +1,156 @@ +libtraceevent(3) +================ + +NAME +---- +tep_register_event_handler, tep_unregister_event_handler - Register / +unregisters a callback function to parse an event information. + +SYNOPSIS +-------- +[verse] +-- +*#include * + +enum *tep_reg_handler* { + _TEP_REGISTER_SUCCESS_, + _TEP_REGISTER_SUCCESS_OVERWRITE_, +}; + +int *tep_register_event_handler*(struct tep_handle pass:[*]_tep_, int _id_, const char pass:[*]_sys_name_, const char pass:[*]_event_name_, tep_event_handler_func _func_, void pass:[*]_context_); +int *tep_unregister_event_handler*(struct tep_handle pass:[*]tep, int id, const char pass:[*]sys_name, const char pass:[*]event_name, tep_event_handler_func func, void pass:[*]_context_); + +typedef int (*pass:[*]tep_event_handler_func*)(struct trace_seq pass:[*]s, struct tep_record pass:[*]record, struct tep_event pass:[*]event, void pass:[*]context); +-- + +DESCRIPTION +----------- +The _tep_register_event_handler()_ function registers a handler function, +which is going to be called to parse the information for a given event. +The _tep_ argument is the trace event parser context. The _id_ argument is +the id of the event. The _sys_name_ argument is the name of the system, +the event belongs to. The _event_name_ argument is the name of the event. +If _id_ is >= 0, it is used to find the event, otherwise _sys_name_ and +_event_name_ are used. The _func_ is a pointer to the function, which is going +to be called to parse the event information. The _context_ argument is a pointer +to the context data, which will be passed to the _func_. If a handler function +for the same event is already registered, it will be overridden with the new +one. This mechanism allows a developer to override the parsing of a given event. +If for some reason the default print format is not sufficient, the developer +can register a function for an event to be used to parse the data instead. + +The _tep_unregister_event_handler()_ function unregisters the handler function, +previously registered with _tep_register_event_handler()_. The _tep_ argument +is the trace event parser context. The _id_, _sys_name_, _event_name_, _func_, +and _context_ are the same arguments, as when the callback function _func_ was +registered. + +The _tep_event_handler_func_ is the type of the custom event handler +function. The _s_ argument is the trace sequence, it can be used to create a +custom string, describing the event. A _record_ to get the event from is passed +as input parameter and also the _event_ - the handle to the record's event. The +_context_ is custom context, set when the custom event handler is registered. + +RETURN VALUE +------------ +The _tep_register_event_handler()_ function returns _TEP_REGISTER_SUCCESS_ +if the new handler is registered successfully or +_TEP_REGISTER_SUCCESS_OVERWRITE_ if an existing handler is overwritten. +If there is not enough memory to complete the registration, +TEP_ERRNO__MEM_ALLOC_FAILED is returned. + +The _tep_unregister_event_handler()_ function returns 0 if _func_ was removed +successful or, -1 if the event was not found. + +The _tep_event_handler_func_ should return -1 in case of an error, +or 0 otherwise. + +EXAMPLE +------- +[source,c] +-- +#include +#include +... +struct tep_handle *tep = tep_alloc(); +... +int timer_expire_handler(struct trace_seq *s, struct tep_record *record, + struct tep_event *event, void *context) +{ + trace_seq_printf(s, "hrtimer="); + + if (tep_print_num_field(s, "0x%llx", event, "timer", record, 0) == -1) + tep_print_num_field(s, "0x%llx", event, "hrtimer", record, 1); + + trace_seq_printf(s, " now="); + + tep_print_num_field(s, "%llu", event, "now", record, 1); + + tep_print_func_field(s, " function=%s", event, "function", record, 0); + + return 0; +} +... + int ret; + + ret = tep_register_event_handler(tep, -1, "timer", "hrtimer_expire_entry", + timer_expire_handler, NULL); + if (ret < 0) { + char buf[32]; + + tep_strerror(tep, ret, buf, 32) + printf("Failed to register handler for hrtimer_expire_entry: %s\n", buf); + } else { + switch (ret) { + case TEP_REGISTER_SUCCESS: + printf ("Registered handler for hrtimer_expire_entry\n"); + break; + case TEP_REGISTER_SUCCESS_OVERWRITE: + printf ("Overwrote handler for hrtimer_expire_entry\n"); + break; + } + } +... + ret = tep_unregister_event_handler(tep, -1, "timer", "hrtimer_expire_entry", + timer_expire_handler, NULL); + if ( ret ) + printf ("Failed to unregister handler for hrtimer_expire_entry\n"); + +-- + +FILES +----- +[verse] +-- +*event-parse.h* + Header file to include in order to have access to the library APIs. +*trace-seq.h* + Header file to include in order to have access to trace sequences + related APIs. Trace sequences are used to allow a function to call + several other functions to create a string of data to use. +*-ltraceevent* + Linker switch to add when building a program that uses the library. +-- + +SEE ALSO +-------- +_libtraceevent(3)_, _trace-cmd(1)_ + +AUTHOR +------ +[verse] +-- +*Steven Rostedt* , author of *libtraceevent*. +*Tzvetomir Stoyanov* , author of this man page. +-- +REPORTING BUGS +-------------- +Report bugs to + +LICENSE +------- +libtraceevent is Free Software licensed under the GNU LGPL 2.1 + +RESOURCES +--------- +https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git